1. Field of Invention
The present invention relates to holographic laser scanning systems that produce an omni-directional scanning pattern in a three-dimensional (3-D) scanning volume wherein users manually transport an object through the 3-D scanning volume to detect physical attributes of the object (such as detecting and decoding bar code symbols on surfaces of the object).
2. Brief Description of the Prior Art
Handheld laser scanning systems typically form a single scan line which must be properly aimed over the surface of its intended target object. Handheld laser scanners such as those described in U.S. Pat. Nos. 4,603,262 and 5,296,689 were developed that used a pointer beam (or aiming light) which is visible over the intended scan distance to aid the user in aiming the handheld scanner (or orienting the target object).
Polygonal laser scanning systems generate a multi-directional scan pattern forming a scan volume which is typically not well-defined. U.S. Pat. No. 6,223,986 discloses a polygonal laser scanning system that employs a laser light source to generate a visible target (or image) in the scan volume at a preferred location for placement of the article to be scanned.
Handheld laser scanning systems and polygonal laser scanning systems are typically limited to scanning applications that require a small scan volume (because it is cost-prohibitive to use such systems to omni-directionally scan a large scan volume).
In contrast, laser scanning systems employing holographic optical elements can be cost-effectively designed and manufactured to produce an omni-directional pattern through a large well-defined scanning volume (preferably with multiple scanning beams with varying depths of field in the scanning volume). The present inventors have recognized the potential to facilitate scanning in 3-D omni-directional holographic laser scanning systems.
In 3-D omni-directional holographic laser scanning systems, such as Metrologic""s HoloTrak(copyright) scanner products, it is often difficult for users to locate the position of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) without looking directly into the scanner and thus exposing the user""s eyes to potentially (or assumed) harmful laser scanning beams. The reason that the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) is not readily visible is due to the high speed of the scanning beams and its relatively low intensity compared to ambient light.
When a user of such a system is required to manually transport an object through the 3-D scanning volume (and the 3-D omni-directional scanning pattern therein) to detect physical attributes of the object (such as detecting and decoding bar code symbols on surfaces of the object), unwanted scanning errors occur in the event that the user is unable to identify the correct location of the 3-D scanning volume (and the omni-directional scan pattern therein) when attempting to transport the object through the 3-D scan volume. Such unwanted scanning errors limit the productivity of the user. Moreover, any time taken by a user in locating the 3-D scanning volume limits the productivity of the user. Such limitations in user productivity represent increased costs associated with the use of the laser scanning system. In addition, a user repetitively searching for the 3-D scanning volume of the system can potentially lead to repetitive motion strain and injury
Thus, there is a great need in the art for an improved holographic laser scanning system that enables users to efficiently locate the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the 3-D omni-directional laser scanning system, while avoiding the shortcomings and drawbacks of prior art holographic scanning systems and methodologies.
Accordingly, a primary object of the present invention is to provide a novel 3-D omni-directional holographic laser scanning system that is free of the shortcomings and drawbacks of prior art laser scanning systems and methodologies.
Another object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that provides visible indicia, visibly discernable by users of the system, characterizing the location of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the system, relative to the physical environment in which the system is installed and operated.
Another object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that provides visible indicia characterizing the approximate location of the center, edges or other portion of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the system.
Another object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that utilizes low cost materials to provide visible indicia characterizing the location of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the system.
Another object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that utilizes a visible light pattern, which is preferably distinguishable from the scanning beam(s) of the system, to provide visible indicia characterizing the location of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the 3-D omni-directional laser scanning system.
Another object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that utilizes a readily-discernable visible light pattern to provide visible indicia characterizing the location of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the system.
Another object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that shines a visible light pattern on a surface over which the objects are moved through the 3-D scanning volume to provide a visible indication of points substantially corresponding to the boundary of the projection of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) onto the surface.
A further object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that uses the same laser scanning beam(s) to detect properties of surfaces passing through a 3-D scanning volume and to provide visible indicia characterizing location of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the system.
A further object of the present invention is to provide a 3-D omni-directional holographic laser scanning system that provides visible indicia characterizing a location of the 3-D scanning volume (and the 3-D omni-directional scan pattern therein) of the system and provides an indication that the user has entered a region corresponding to the 3-D scanning volume.
These and other objects of the present invention will become apparent hereinafter and in the claims to Invention.